1. Field of the Invention
This invention relates to the field of marine dredging.
2. Description of the Related Art
An apparatus identified by the trade name "Cable Arm Clamshell" is advertised as an environmental dredging device by Cable Arm Incorporated of Trenton, Mich. Their literature states that a patent is pending. This cable operated device differs from a conventional grab type of dredge commonly known as a "clamshell bucket" in that it is less prone to spill excess soil due to the buckets forming a nominally closed compartment when the buckets are in the fully closed position.
My invention differs from the Cable Arm apparatus in several aspects. My apparatus provides a soil receiver chamber with an air-void so that water does not have to be displaced from the dredge by the incoming soil. Water must flow out of the Cable Arm apparatus in a volume equal to the dredged soil. My apparatus has its scoop buckets hinged to a soil receiver chamber whereas the Cable Arm apparatus has its scoop buckets hinged to each other as is done with a conventional clamshell dredge. Furthermore, the Cable Arm apparatus does not provide deployable silt curtains. In addition, the Cable Arm apparatus does not provide means of jet water washing the interior of the buckets.
A proprietary clamshell dredge is depicted in promotional literature provided by Dow Environmental Incorporated of Rockville, Md. This apparatus appears to be a conventional clamshell bucket with additional metal plating added to the sides and tops of the buckets to provide a nominally closed compartment when said buckets are in the fully closed position. The company's literature makes no claim of patents issued or pending.
My invention differs from the Dow Environmental apparatus in several aspects. Again, my apparatus provides a soil receiver chamber with an air-void so that water does not have to be displaced from the dredge by the incoming soil and the Dow device has no such feature. Furthermore, the Dow apparatus does not provide deployable silt curtains. In addition, the Dow apparatus does not provide means of jet water washing the interior of the buckets.